Radio changes volume by itself while moving

Hi fellow car lovers,

We have a 2007 Mitsubishi Pajero (not sure the current equivalent in US, it used to be the Montero but I think they have since discontinued it). It’s a great car.

One rather annoying issue we are having with it at the moment…

The radio changes volume by itself. It goes up, it goes down, all on it’s own without any input from us. Here are some observations:

  • Only happens when the car is in motion, at a stand-still it is fine.
  • Only happens when listening to radio, not CD player or DVD player.
  • The car does not have a “knob” for the volume, it is just buttons (rules out potentiometer thingy)

There are steering wheel controls, but the fact that the volume changes only happen when listening to the radio, and not CD, make me believe it’s not those. Same with speed-sensitive volume controls. We have turned those off in the settings and it still does the same. Even with them on or off, the CD volume works as expected.

Does anyone have any ideas what’s going on?


My Pontiac does that. Its a feature to keep the volume at a constant level as road noise increases. I like it. I believe there is an option to turn the feature off so might want to take a look in the owners manual.

Agree with bing, sounds like speed compensated volume control. Hondas have it as well, you just need to read the manual on how to shut it off.

Just throwing something out there but if this car is not equipped with a speed compensated volume control it’s also quite possible the problem could be a faulty radio head; manual potentiometer or not. Even the button types can go stupid at times.

Just a few months ago I had to change the radio head out in my Lincoln as it had developed 2 problems; both due to the washboard roads that are beating things to death. One was the CD skipping and the other was the volume/ON/OFF controls which had developed a mind of their own.
At times the radio would pop on or off and at other times the volume would rise without any input from the driver.

Well, I am sure it’s not the speed compensated volume thingy… as we have turned it off (and on) and the issue still occurs in both settings.

I am not sure it could be the buttons themselves, as the issue only happens when listening to the radio. CD plays just fine with no changes in volume.

I don’t think it’s a signal strength issue either since we live in the middle of the city and it can fluctuate volume even when the car is stationary.

Has anyone had this problem before?

Thanks for the replies!

Regardless of what you find I’m betting the only way to solve the problem will be to replace the radio. Your radio probably has some kind of volume indicator, a bar graph, or number. Mine briefly displays a number when the volume is changed. If that isn’t changing when volume of the radio changes then the problem, as you have guessed, probably isn’t with the main amplifier.Each component in your system has its own pre-amplifier. My guess, the pre-amplifier for the radio has gone glitchy.

Car radios are 100% disposable, non-repairable, products…

There are a number of places where you can send your defective radio into and have them fix it, though if it is just a standard unit it may not be cost effective to do that. More expensive units can be worth fixing, especially over the dealer cost of a new unit. The trouble you are having does sound like a problem inside the radio section and replacing it may be the best solution to the problem. Ebay is a good place to find original replacement units. That way all your external controls for the system will still work.

Just make sure you get the security code for the new radio if you buy off ebay. That and Craigs list is where stolen ones get dumped.

I was considering replacing it anyways I guess. My only concern if it’s not within the radio, and it’s a problem with the antenna/connection… how can I diagnose this?


You have to check the owner’s manual and see if your car is equipped with volume adjustment for speed and how to disable it. If you don’t have this option, then I would just change the radio with a decent aftermarket one.

Crutchfield has a lot of info and selection, with installation guides and accessories.

You don’t have to be concerned about this trouble being external to the radio. A faulty antenna would be a different problem, like not picking up any stations. The trouble you describe has to do with the audio gain for the radio section, which is done inside the radio. If the external volume control was a problem I would think the other functions would be effected also and not just the radio.

The radio in my 98 Pathfinder did this. It was a known problem with all systems made by Clarion back then. So it may be the head unit.

Alpine makes some of the best head units out there. that being said they also =have units that with an adp. that will let the remote radio controls work with your new radio. I have owned about 5 different Alpines over the years never one had any problems over the years. Cruthchfield does have a lot of good info. pay a visit to a local mobil electrincs store and talk to them. there our other brands out there that our very nice and won’t break the bank. when shopping also check out the instale bay at the store your thinking about doing bussenesss with, is it while lite, clean does the techs take pride in what they do? do they show the same care about changing the radio in your car vs. doing a very large a/v system with all the bells.

I have the EXACT same problem in my Prius V 2012. It doesn’t happen with satellite radio, CD, or Bluetooth, just the radio. I bought the car used and had custom racks drilled into my roof right after purchasing so the dealership is saying they must have knicked a wire, but the rack people say no way. I’m dying to know if you ever found the problem! Thx

Haha this post was so long ago I thought I would forever be the only one.

No sadly still haven’t figured out the problem nor a solution. Some people said maybe bad antenna connection but I never investigated. Possibly bad grounding was mentioned as well. I had been intending to just replace the whole unit but it’s one of those premium sound systems that won’t cope with hot swapping a new eBay unit in. So basically we just listen to podcasts and music from iPod, if we use radio we just live with it.

I would be skeptical about the dealer saying drilling holes into the roof caused this… Most cars I have seen the antenna runs along the headliner inside from the roof not near where a roof rack would go. Who knows… You are the only person to ever reply to me saying you had the same problem haha

Hopefully you have better luck than me!

Kudos on the tests you’ve used to eliminate some of the possibilities.
Since you’ve eliminated them, my money is on the radio.
This is just a wild guess, but I’ll bet there’s a preamp in the radio circuitry that’s not used in the CD player circuit. These units are no longer made to be repaired, and even if it could be I doubt if you could find a repair shop to do it. If you did, it would probably cost a lot more to repair it than to replace the radio. You can buy a new unit for the cost of one (perhaps two) hours of shop time. Individual parts probably couldn’t even be purchased by a tech. An individual part used to be a wirewound resister, or a capacitor, or a transistor, or something of that sort. Now it’s all in thin-film “chips”. And the frame structures are now all ultrasonically welded plastics or “pop in” parts with little plastic bifurcated “mushrooms” that cannot be disassembled nondestructively once popped together.

NOTE" should you decide to replace the unit yourself, I strongly urge you to spend the extra $20 on an “adapter cable”. This is spliced onto the new unit’s leads on the kitchen table following easy-to-follow directions and then plugs directly into your OEM wiring harness. Installation of the radio is much, much easier and the problems often associated with butchered wiring harnesses are avoided. If you have a shop install the new unit, INSIST that they use an adapter cable. If they give you and argument, go elsewhere.

I’ve installed a few radios and CD players over the years, and there’s absolutely no way I’d do it (or allow anyone else to) without an adapter cable.

Unless the radio is connected directly to the CAN bus, I’m guessing there must be an input for the speed sensor. There must also be some voltage level that can be measured when the car is not moving. If that sensor input can be disconnected and the input is fed with that stationary voltage, you should be okay. Just a thought.

If it was related to the radio signal wouldn’t it be staticky instead of the volume dipping? But, since it only occurs when in motion then it makes me think there is noise interfering with the signal. And, since satellite radio is fine then it’s specifically that wire.

The racks are mounted into the roof right where the radio wire runs, but since it is typically taped to the headliner the gap should have prevented damage.

Any advice is appreciated!

Hello, this is a very old thread, but we are facing the same issue in our new MG RX5. The radio volume fluctuates, and it is a very annoying issue. If anyone has the same experience, kindly let us know how you found a solution.